According to Bischoff and Hiss, the impregnation takes place in the distal end of the tube. After impregnation the zygote continues its wandering by the current of the ciliated epithelia of the tube, towards the uterus. The ovum needs, according to Hensen, from three to five days, according to Bischoff eight days, to transverse this way, in the woman. It could not last any longer, says Von Winckel, because the uterine end of the tube, in the human female, has a diameter of only two to three millimeters, while the diameter of the ovum, in the second week of pregnancy, is three to six millimeters already. Hence, when a retardation, for one cause or another, takes place, a tubal pregnancy will be the result. When the impregnated ovum has reached the cavity of the uterus it penetrates through the epithelium into the submucous fibrous tissues of the uterus, where it completes its development. _Internal ovarian secretion._—Besides the function of preparing the ova, the ovary has an internal secretion which is the cause of the female secondary characteristics. When both ovaries are removed before puberty, the time when the stamp of sex is becoming impressed on every part of the body, the essential feminine features fail to develop. The absence of the ovaries leads to the development of a colorless, neuter creature of angular form, strident voice, striding gait, and even of bearded chin. _Function of the Fallopian tubes._—The function of the ducts is to furnish a path for the ovum in its passage towards the uterus and for the spermatozoa on their way to meet the ovum. The current of the tubal ciliated epithelia is directed towards the uterus. In this way the ovum which does not possess self-motion, as do the spermatozoa, is carried towards its destination, while the spermatozoa have to swim against the current.